Timing based servo arrangements are employed with respect to longitudinal tape media, for example, in magnetic tape systems, to provide track following capability. Recorded servo patterns comprise dual transitions typically arranged as stripes recorded at more than one azimuthal orientation or slope across the tape media. The technology is discussed in the incorporated '384 patent. The timing between the stripes of any pair of stripes having different azimuthal orientations thus varies continuously as a read head is moved in the lateral direction across the servo track. The pattern is read by a servo read head whose width is small compared to the servo pattern width, and servo head lateral position is derived from the relative timing of pulses generated by crossing transitions of the stripe edges as the tape is moved in the longitudinal direction. A leading edge of a stripe comprises a transition of a first polarity and a trailing edge of a stripe comprises a transition of a second polarity opposite to that of the first polarity. Position sensing with this system is achieved by deriving a ratio of two servo pattern intervals, one pattern interval comprising the timing between the same edge of stripes having different azimuthal orientations, and the other pattern interval comprising the timing between the same edge of stripes having the same azimuthal orientation. Thus, the position sensing is ratio oriented and is insensitive to tape speed.
A typical way to determine which stripe is being read is to arrange the stripes into patterns of frames, each frame having two sub-frames, each with two bursts of stripes arranged in different azimuthal orientations. A pattern interval is provided within a sub-frame, another pattern interval is between sub-frames, and further intervals are between frames.
Different types of servo patterns are provided with alternate servo pattern geometries in which the azimuthal orientations or slopes are different as are the stripe width and stripe spacing. The type of servo pattern may be determined from a cartridge memory carried with a magnetic tape in the cartridge containing the magnetic tape. There may be cases in which the cartridge memory is missing or the information it contains is corrupted.